Abstract:

Methods and compositions for the deposition of a film on a substrate. In
general, the disclosed compositions and methods utilize a precursor
containing calcium or strontium.

Claims:

1. A method of depositing an alkali earth metal containing film on one or
more substrates, comprising:a) providing at least one substrate disposed
in a reactor;b) introducing a first precursor in vapor form into the
reactor,wherein the first precursor has the general
formula:M(RxCp)2 and wherein:is calcium or strontium;R is
independently selected from: H; and a C1-C6 linear, branched, or cyclic
alkyl group; and0.ltoreq.×≦5; andc) depositing at least part
of the first precursor to form an alkali earth metal containing film on
the one or more substrates.

2. The method of claim 1, wherein the first precursor comprises at least
one member selected from the group consisting of: Ca(iPr3Cp)2;
Ca(Me5Cp)2; Ca(tBu3Cp)2; and Ca(EtCp).sub.2.

3. The method of claim 1, wherein the first precursor comprises at least
one member selected from the group consisting of: Sr(iPr3Cp)2;
Sr(Me5Cp)2; Sr(tBu3Cp)2; and Sr(EtCp).sub.2.

4. The method of claim 1, wherein the first precursor is adducted with at
least one member selected from the group consisting of: dimethoxyethane;
diethylether; acetonitrile; tetrahydrofuran; triglyme; tetraglyme;
triene; and tetraene.

6. The method of claim 1, further comprising introducing a second
precursor gas into the reactor, wherein the second precursor comprises at
least one metal selected from the group consisting of: Cu; Pr; Mn; Ru;
Zr; Hf; Ln: and combinations thereof.

7. The method of claim 1, further comprising introducing at least one
oxygen containing reactant into the reactor, wherein the oxygen
containing reactant comprises at least one member selected from the group
consisting of: ozone; oxygen; water; nitric oxide; and carboxylic acid.

8. The method of claim 1, further comprising depositing the alkali earth
metal containing film through a chemical vapor deposition (CVD) process
or an atomic layer deposition (ALD) process.

[0003]This invention relates generally to compositions, methods and
apparatus for use in the manufacture of semiconductor, photovoltaic,
LCD-TFT, or flat panel type devices. More specifically, the invention
relates to methods and compositions for depositing alkali earth metal
thin films, with superconductive or magnetoresistance properties, on a
substrate.

[0004]2. Background of the Invention

[0005]As the design and manufacturing of semiconductor devices continues
to evolve, the semiconductor industry is constantly seeking new and novel
methods of depositing films onto substrates, such that the resulting film
will have certain sought after properties. Two such examples of sought
after properties are films which exhibit superconductive-like or
magnetoresistance properties. Field effect transistors (FET) with a
semiconductor channel make use of an oxide superconductor material in the
gate electrode, which can provide control of parasitic resistance,
capacitance, and a proper work function when operated at an adequate
temperature. Magnetoresistance materials are used in hard drive
applications, and allow for better density and capacity of storage in the
resultant devices.

[0006]Films utilizing calcium and strontium, especially such films with a
perovskite-type structure, have been examined for these superconductive
and magnetoresistance applications. Some of the structures which have
shown promise for these applications include: CaCu3Ti4O.sub.12;
CaTiO3; (PrCa)MnO3; (Ca, Mn,Sr)RuO3;
ZrO2--CaO--ZrO2; HfO2--CaO--HfO2; Ca:ZrO2;
Ca:HfO2; Ca:Ln2O3.

[0007]In the case of calcium/hafnium structures, because of its ability to
form solid solutions and ternary crystalline phases, calcium oxide is an
appropriate additive to HfO2. Stoichiometric compounds with low
defects should form relatively easily, compared to mixtures of
Al2O3 and HfO2. CaO has a wide band gap (6.8 eV), which
might be suitable in dielectric stacks with HfO2 for instance.

[0008]With its perovskite structure, CaHfO3 has been considered as an
interesting material for gate capacitor dielectric in
metal-oxide-semiconductor field-effect-transistor (MOSFET) with Si or
SrTiO3 channels.

[0009]Calcium oxide films have been obtained by atomic layer deposition
(ALD) process using calcium β-diketonate, O2 and ozone. The
material first formed was calcium carbonate which turned into CaO after
heat treatment at 670° C. in CO2-free atmosphere.

[0010]Consequently, there exists a need for methods and materials to
deposit thing films containing calcium and strontium.

BRIEF SUMMARY

[0011]Embodiments of the present invention provide novel methods and
compositions for the deposition of a film on a substrate. In general, the
disclosed compositions and methods utilize a precursor containing calcium
or strontium.

[0012]In an embodiment, a method for depositing an alkali earth metal
containing film on one or more substrates comprises providing at least
one substrate disposed in a reactor. A vapor form precursor is introduced
into the reactor. The precursor has the general formula:

M(RxCp)2

wherein M is calcium or strontium, each R is independently either H or a
C1-C6 linear, branched, or cyclic alkyl group, and
0≦×≦5. At least part of the precursor is deposited on
one or more of the substrates to form a film which has
superconductor-like or magnetoresistance properties.

[0013]Other embodiments of the current invention may include, without
limitation, one or more of the following features: [0014]the first
precursor is one of Ca(iPr3Cp)2; Ca(Me5Cp)2;
Ca(EtCp)2; Ca(tBu3Cp)2; Sr(iPr3Cp)2;
Sr(Me5Cp)2; Sr(tBu3Cp)2; and Sr(EtCp)2;
[0015]the first precursor has at least two anionic ligands to the calcium
or strontium; [0016]the first precursor is adducted with at least one of:
dimethoxyethane (DME), tetrahydrofuran (THF); diethylether; acetonitrile;
triglyme; tetraglyme; triene; and tetraene; [0017]the first precursor is
initially supplied blended with at least one of: toluene; benzene;
pentane; hexane; cyclohexane; heptane; tetrahydrofuran; chloroform;
dichloromethane; ethyl acetate; acetonitrile; dimethylformamide; ethanol;
methanol; propanol; isopropanol; butanol; mesitylene; butylacetate;
xylene; and octane; [0018]a second precursor is introduced into the
reactor, and the second precursor contains at least one metal selected
from: Cu; Pr; Mn; Ru; Zr; Hf; and Ln; [0019]an oxygen containing reactant
is introduced into the reactor, wherein the reactant is selected from:
ozone; oxygen; water; nitric oxide; and a carboxylic acid; [0020]the
deposition process for depositing the film is either a chemical vapor
deposition (CVD) or atomic layer deposition (ALD) type process, and
either may type be a plasma enhanced process; [0021]the deposition
process is performed at temperature between about 100° C. and
about 600° C.; [0022]the deposition process is performed at a
pressure between about 0.1 mTorr and about 100 Torr; and [0023]the
deposited film is a (Pr,Ca)MnO3 type film.

[0024]The foregoing has outlined rather broadly the features and technical
advantages of the present invention in order that the detailed
description of the invention that follows may be better understood.
Additional features and advantages of the invention will be described
hereinafter that form the subject of the claims of the invention. It
should be appreciated by those skilled in the art that the conception and
the specific embodiments disclosed may be readily utilized as a basis for
modifying or designing other structures for carrying out the same
purposes of the present invention. It should also be realized by those
skilled in the art that such equivalent constructions do not depart from
the spirit and scope of the invention as set forth in the appended
claims.

Notation and Nomenclature

[0025]Certain terms are used throughout the following description and
claims to refer to various components and constituents. This document
does not intend to distinguish between components that differ in name but
not function.

[0027]As used herein, the abbreviation, "Me," refers to a methyl group;
the abbreviation, "Et," refers to an ethyl group; the abbreviation,
"t-Bu," refers to a tertiary butyl group, the abbreviation, "Cp", refers
to a cyclopentadienyl group; and the abbreviation "iPr3Cp" refers to
1,2,4-tri-isopropylcyclopentadienyl.

[0028]As used herein, the term "superconductor" when applied properties or
materials refers to properties or materials which exhibit little to no
electrical resistivity, and which when in bulk, exhibit no magnetic
field.

[0029]As used herein, the term "magnetoresistant or magnetoresistance"
when applied to properties or materials refers to the changing of the
electrical resistance of a material when an external magnetic field is
applied.

[0030]As used herein, the term "independently" when used in the context of
describing R groups should be understood to denote that the subject R
group is not only independently selected relative to other R groups
bearing different superscripts, but is also independently selected
relative to any additional species of that same R group. For example, in
the formula MR1x (NR2R3).sub.(4-x), where x is 2 or
3, the two or three R1 groups may, but need not be identical to each
other or to R2 or to R3. Further, it should be understood that
unless specifically stated otherwise, values of R groups are independent
of each other when used in different formulas.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0031]Embodiments of the present invention provide novel methods and
compositions for the deposition of a film on a substrate. In general, the
disclosed compositions and methods utilize a precursor containing calcium
or strontium.

[0032]In an embodiment, a method for depositing an alkali earth metal
containing film on one or more substrates comprises providing at least
one substrate disposed in a reactor. A vapor form precursor is introduced
into the reactor. The precursor has the general formula:

M(RxCp)2

wherein M is calcium or strontium, each R is independently either H or a
C1-C6 linear, branched, or cyclic alkyl group, and
0≦×≦5. At least part of the precursor is deposited on
one or more of the substrates to form a film which has
superconductor-like or magnetoresistance properties.

[0034]In an embodiment, a precursor in vapor form is introduced into a
reactor. The precursor in vapor form may be produced by vaporizing a
liquid precursor solution, through a conventional vaporization step such
as direct vaporization, distillation, or by bubbling an inert gas (e.g.
N2, He, Ar, etc.) into the precursor solution and providing the
inert gas plus precursor mixture as a precursor vapor solution to the
reactor. Bubbling with an inert gas may also remove any dissolved oxygen
present in the precursor solution.

[0035]The reactor may be any enclosure or chamber within a device in which
deposition methods take place such as without limitation, a cold-wall
type reactor, a hot-wall type reactor, a single-wafer reactor, a
multi-wafer reactor, or other types of deposition systems under
conditions suitable to cause the precursors to react and form the layers.

[0036]Generally, the reactor contains one or more substrates on to which
the thin films will be deposited. The one or more substrates may be any
suitable substrate used in semiconductor, photovoltaic, flat panel or
LCD-TFT device manufacturing. Examples of suitable substrates include
without limitation, silicon substrates, silica substrates, silicon
nitride substrates, silicon oxy nitride substrates, tungsten substrates,
or combinations thereof. Additionally, substrates comprising tungsten or
noble metals (e.g. platinum, palladium, rhodium or gold) may be used. The
substrate may also have one or more layers of differing materials already
deposited upon it.

[0037]In some embodiments, in addition to the precursor vapor solution, a
reactant gas may also be introduced into the reactor. The reactant gas
may be one of oxygen, ozone, water, hydrogen peroxide, nitric oxide,
nitrogen dioxide, radical species of these, as well as mixtures of any
two or more of these.

[0038]In some embodiments, and depending on what type of film is desired
to be deposited, a second precursor gas may be introduced into the
reactor. The second precursor gas comprises another metal source, such as
copper, praseodymium, manganese, ruthenium, zirconium, hafnium, or
lanthanum.

[0039]The first precursor and any optional reactants or precursors may be
introduced sequentially (as in ALD) or simultaneously (as in CVD) into
the reaction chamber. In some embodiments, the reaction chamber is purged
with an inert gas between the introduction of the precursor and the
introduction of the reactant. In one embodiment, the reactant and the
precursor may be mixed together to form a reactant/precursor mixture, and
then introduced to the reactor in mixture form. In some embodiments, the
reactant may be treated by a plasma, in order to decompose the reactant
into its radical form. In some of these embodiments, the plasma may
generally be at a location removed from the reaction chamber, for
instance, in a remotely located plasma system. In other embodiments, the
plasma may be generated or present within the reactor itself. One of
skill in the art would generally recognize methods and apparatus suitable
for such plasma treatment.

[0040]In some embodiments, the temperature and the pressure within the
reactor are held at conditions suitable for ALD or CVD depositions. For
instance, the pressure in the reactor may be held between about 0.0001
and 1000 torr, or preferably between about 0.1 and 10 torr, as required
per the deposition parameters. Likewise, the temperature in the reactor
may be held between about 50° C. and about 600° C.,
preferably between about 200° C. and about 500° C.

[0041]In some embodiments, the precursor vapor solution and the reaction
gas, may be pulsed sequentially or simultaneously (e.g. pulsed CVD) into
the reactor. Each pulse of precursor may last for a time period ranging
from about 0.01 seconds to about 10 seconds, alternatively from about 0.3
seconds to about 3 seconds, alternatively from about 0.5 seconds to about
2 seconds. In another embodiment, the reaction gas, may also be pulsed
into the reactor. In such embodiments, the pulse of each gas may last for
a time period ranging from about 0.01 seconds to about 10 seconds,
alternatively from about 0.3 seconds to about 3 seconds, alternatively
from about 0.5 seconds to about 2 seconds.

[0042]In an embodiment, the precursor may be Ca(iPr3Cp)2, which
in comparison to other precursors such as Ca(tmhd)2, exhibits good
volatility properties. Ca(iPr3Cp)2 may be used with
Pr(tmhd)3, Mn(tmhd)2, and an oxygen containing reactant to
deposit a (Pr,Ca)MnO3 film.

[0043]While embodiments of this invention have been shown and described,
modifications thereof can be made by one skilled in the art without
departing from the spirit or teaching of this invention. The embodiments
described herein are exemplary only and not limiting. Many variations and
modifications of the composition and method are possible and within the
scope of the invention. Accordingly the scope of protection is not
limited to the embodiments described herein, but is only limited by the
claims which follow, the scope of which shall include all equivalents of
the subject matter of the claims.